This application is a continuation-in-part and incorporates by reference the content of the patent application for the “Inverted Wankel” (application Ser. No. 11/361,235 by Webb, henceforth “the '235 application”). The '235 application discloses an engine that is an inversion of the standard Wankel rotary engine. In the engine of the '235 application, the stator has a “constant-width” geometry: it always appears to be the same width when viewed from any angle. The particular constant-width shape of the '235 application is the same as that used as a rotor in production rotary engines and is based on a Reuleaux triangle, named for the French mathematician who formally described it. In the '235 application, the rotor, stator and shaft seals define a chamber having epitrochoidal geometry, so that regions of gas in the engine housing may undergo compression and ignition as a result of the rotor motion.
Although the Inverted Wankel engine disclosed in the '235 application represents a significant advancement in the art, and may open up new fields of application for the Wankel engine, it includes some mechanical complexity that may drive up the cost of manufacture. Also, the minimum size and weight of an engine made according to the '235 application disclosure may be greater than would be desirable for some applications.